Study of electrical and optical properties of InGaN/AlGaN double heterostructure blue light emitting diodes

The electrical and optical properties of double heterostructure blue light-emitting diodes, with an In_0.06Ga_0.94N:Zn,Si active layer, made by Nichia Ltd., were investigated at various temperatures. Measurement of the forward bias current-voltage behavior of the device demonstrates a departure from the Shockley model of p-n diodes, and it is observed that the dominant mechanism of carrier transport across the junction is associated with carrier tunneling. Electroluminescence experiments of the devices indicates that there is an emission peak located at 2.80 eV, and a relatively weaker short-wavelength peak at 3.2 eV. A significant blue shift of the optical emission peak, consistent with the tunneling character of electrical characteristics, was observed. Furthermore, we studied the properties of electroluminescence under various pulsed currents, and a degradation in I-V characteristics and a low resistance ohmic short were observed